Separate out idr_mark_full() from sub_alloc() and make marking theallocated slot full the responsibility of idr_get_new_above_int().

Allocation part of idr_get_new_above_int() is renamed toidr_get_empty_slot(). New idr_get_new_above_int() allocates a slotusing the function, install the user pointer and marks it full usingidr_mark_full().

This change doesn't introduce any behavior change. This will beused by ida.